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Flu(lat. Influenza) is an acute infectious disease of the respiratory tract caused by the influenza virus. The causative agent of influenza is a virus of three serotypes - A, B, C.

Flu - causes (etiology)

The source of influenza infection is a sick person, who is dangerous in the first days of illness, when the virus is intensely released into the environment. Transmission of infection occurs mainly by airborne droplets.

The causative agents of influenza belong to the orthomyxovirus family, which includes the genus of influenza A viruses, the genus of influenza B and C viruses. Influenza A viruses are divided into many serotypes. New antigenic variants are constantly emerging. The influenza virus is quickly killed by heating, drying and under the influence of various disinfecting agents. The gates of infection are upper sections respiratory tract. The influenza virus selectively infects the columnar epithelium of the respiratory tract, especially the trachea. Increased permeability vascular wall leads to disruption of microcirculation and the occurrence of hemorrhagic syndrome (hemoptysis, nosebleeds, hemorrhagic pneumonia, encephalopathy). Influenza causes a decrease in immunological reactivity. This leads to an exacerbation of various chronic diseases - rheumatism , chronic pneumonia, pyelitis, cholecystitis , dysentery, toxoplasmosis, etc., as well as to the emergence of secondary bacterial complications. The virus usually persists in the patient’s body for 3-5 days from the onset of the disease, and when complicated by pneumonia – up to 10-14 days.

Influenza – mechanism of occurrence and development (pathogenesis)

The influenza virus enters the respiratory tract of an infected person and then invades epithelial cells. The spread of the virus occurs through airborne droplets during coughing and sneezing, although infection is also possible through a handshake, other personal contacts, and through various objects. Experimental evidence suggests that the spread of infection in a fine aerosol (consisting of particles with a diameter less than 10 microns) is more effective than in an aerosol with larger droplets. The virus initially infects cells of the ciliated columnar epithelium, but then invades other cells of the respiratory tract, including alveolar cells, mucocytes and macrophages. Virus replication lasts 4-6 hours in infected cells, then the active virus leaves the cell and enters a nearby one. As a result, within a few hours the pathological process from small foci spreads over a significant cellular surface of the respiratory tract. For experimentally induced infection, the incubation period varied from 18 to 72 hours. Using histopathological methods, granulation, vacuolization, swelling and formation of pyknotic nuclei, followed by necrosis and desquamation of cells were detected in infected cells. In some areas, the columnar epithelium was replaced by flat and metaplastic epithelial cells. The severity of the disease correlated with the amount of virus present in the mucous secretion. This suggests that the extent of viral replication may be an important mechanism of pathogenesis pathological process. Despite the presence of such common features illnesses such as fever, headache and myalgia, influenza virus is rarely found in extrapulmonary areas, including the bloodstream. In this regard, the pathogenesis systemic symptoms influenza remains unknown.

The body's response to influenza infection is complex. defense mechanisms, including the formation of serum and secretory antibodies, cellular immune response, interferon activation, etc. Changes in serum antibody levels can be detected using a variety of methods as early as 2 weeks after the initial introduction of the influenza virus. These antibodies can be detected by hemagglutination inhibition (HAI), complement fixation (FC), neutralization, solid-phase enzyme immunoassay(ELISA) and determination of anti-neuraminidase antibodies. Antibodies against hemagglutinins are probably the most important factor in immunity. It has been shown that when the antibody titer in the PHA reaction is at least 1:40, infection does not develop. Secretory antibodies produced in the respiratory tract belong predominantly to the IgA class and also play a role important role in protecting the body from infection. It has been shown that when the neutralizing titer of secretory antibodies is 1:4 or higher, infection does not develop. Already in early dates after the onset of the infectious process, cellular immune reactions appear, both antigen-specific and antigen-nonspecific. Their severity depends on the initial level of the host’s own immunity. These reactions include an increase in the proliferative and cytotoxic activity of T cells and the activity of natural killer cells. Immediately after the virus enters the respiratory tract, the formation of interferons begins in the body, and an increase in their titers coincides with a decrease in the release of viruses into the external environment.

The macroorganism factors responsible for stopping the release of the virus into the external environment and for resolving the infectious process have not been specifically studied. The release of the virus into the external environment usually stops within 2-5 days after the first signs of the disease appear. During this time, changes in serum and secretory antibody levels are often undetectable by conventional methods, although even on early stages a rise in antibody levels can be detected by highly sensitive methods, particularly in individuals with pre-existing immunity as a result of past infection. It has been suggested that interferon, cellular immune responses, or nonspecific inflammatory responses play an important role in the resolution of the infectious process.

Flu - pathological anatomy

The pathological anatomy of influenza varies depending on the absence or presence of secondary infection and its severity. In the first case, the changes are caused by the virus itself, in the second - by attached microbes.

In this regard, there are two types of influenza:

• toxic flu, or acute influenza toxicosis;
• influenza with damage to the respiratory organs.

Toxic flu is characterized by changes in the epithelium of the respiratory tract and circulatory disorders. There is desquamation of epithelial covers damaged by the virus throughout the respiratory tract. In the desquamated epithelial cells of the nasal turbinates, fuchsinophilic bodies, microcolonies of the virus containing ribonucleic acid, are found. The detection of such cells with inclusions in a smear from the nasal mucosa can have diagnostic value.

Later, regeneration of the epithelium occurs. Circulatory disorders are expressed by hyperemia and hemorrhages in the mucous membrane, stasis in it and in lung tissue, the formation of hyaline PIC-positive membranes in the latter. Circulatory disorders are observed in the central nervous system and other organs. On serous membranes pinpoint hemorrhages are visible. The lymph nodes, especially the neck, and the spleen are enlarged due to acute hyperplasia. All the described changes occur as a result of the direct effect of the virus and its toxins on tissue.

Flu - symptoms (clinical picture)

There are no characteristic signs to differentiate between sporadic diseases of influenza A, B, C.

A feature of influenza infection is an earlier and more rapid increase in toxicosis compared to symptoms of damage to the upper respiratory tract.

Influenza usually begins acutely, a few hours or 1-2 days after infection. The temperature can quickly rise to 39-40°C. Older children complain of headaches and muscle pain, weakness, younger children become lethargic and restless. The acute period of the disease may be accompanied by vomiting, delirium, convulsions, meningeal symptoms, abdominal syndrome(abdominal pain, vomiting, increased bowel movements). Cyanosis of the nasolabial triangle and lips, facial hyperemia, injection of the sclera of the eyes and conjunctiva appear early; Possible nosebleeds and hemorrhagic rash on visible mucous membranes and skin.

Symptoms of damage to the upper respiratory tract, as a rule, appear on the 2nd day of the disease and are usually mild at first: the nose is stuffy or there is slight mucous discharge, a dry cough appears, which often becomes obsessive and painful on the 2-3rd day. Respiratory or viral croup and asthmatic syndrome may develop.

When examining the lungs of children, especially infants, a boxy tone of percussion sound is determined, hard breathing is heard with isolated dry, sometimes coarse-bubbling wet rales. In infants with these changes in the lungs, respiratory failure develops II-III degrees, which is caused by damage to interstitial tissue.

When a bacterial infection develops, fine tissue is attached to the lesion of interstitial tissue. focal pneumonia.

Most children in the acute period experience muffled heart sounds, some develop systolic murmur varying intensity. In most patients, these phenomena disappear within 2-3 weeks from the onset of the disease, but in some they can be detected within 2-3 months. From others internal organs No special violations are usually observed. Changes in the blood picture are atypical.

Unlike older children, most young children often experience a gradual onset of the disease with an increase in body temperature only to subfebrile levels, and the leading signs of intoxication are lethargy, drowsiness, decreased or lack of appetite, and vomiting. However, it is these children who develop especially often and early severe complications (focal pneumonia, otitis, otoanthritis), which significantly aggravates the course of the disease and aggravates the prognosis.

In the absence of complications, on the 3-5th day of illness the body temperature decreases, but recovery occurs slowly.

Depending on the severity of the main symptoms and the severity of the course, the following are distinguished (according to S. D. Nosov): clinical forms flu:

• catarrhal - with pronounced symptoms of catarrh of the respiratory tract, but without severe toxicosis;
• toxic - with severe disturbances general condition, hyperthermia, damage to the nervous and cardiovascular systems, etc.;
• subtoxic - with the same phenomena as in the toxic form, but moderately expressed;
• toxic-catarrhal.

Besides these typical forms influenza, there are atypical:

• erased form, occurring without pronounced catarrh of the respiratory tract and intoxication;
• hypertoxic (fulminant) form, which is characterized by a violent onset, severe toxicosis, reaching a coma.

In terms of severity, influenza, like other acute respiratory diseases, can be heavy, medium-heavy and light. The severity criteria are:

• severity of temperature reaction;
• the degree of impairment of the general condition;
• the degree of dysfunction of the main body systems (nervous, cardiovascular, respiratory, etc.).

Flu - treatment

In most cases, patients are prescribed treatment at home, with the exception of seizures, hyperthermia, meningeal syndrome, and frequency disorders. heart rate, disorders of consciousness and other critical symptoms.

If symptoms of the disease occur, you should not self-medicate to avoid possible complications. In some cases, the doctor prescribes additional tests - for example, an ECG or chest x-ray.

Self-administration of antibiotics is especially dangerous, leading to the development of dysbacteriosis and chronic forms diseases.

Typically, anti-influenza therapy includes the following:

• plenty of hot drinks (tea, berry juice, alkaline mineral water), inhalations with herbs;
• antipyretics, the dosage of which should take into account the patient’s age;
• local vasoconstrictors(nasal sprays);
• expectorants;
• antitussives (selection is carried out depending on the type and intensity of cough;
• antiviral drugs are especially effective in the first days of the disease when administered intranasally;
• multivitamins, ascorbic acid.

Flu - prevention

To prevent the spread of the virus, it is necessary to use gauze bandages, ventilate the room and disinfect the air through quartz treatment. Can also be used intranasally oxolinic ointment, quite effective means Vaccination is recommended, which must be done in mid-autumn and again in mid-winter.

Amantadine and rimantadine, currently used for the prevention and treatment of influenza, are effective only against type A viruses. Recently isolated strains of influenza virus that are resistant to these drugs lead to the spread of infection, even despite treatment, and are most dangerous in groups.

Some antiviral drugs (arbidol) have specificity for influenza virus types A and B, but they have a number of undesirable side effects, and one of these effects is hepatotoxicity.

The latest development is a drug that specifically inhibits the viral enzyme neuraminidase. But this drug has not yet been registered in Russia. According to preliminary data, this drug has a 70 percent preventive effectiveness against influenza, and also significantly reduces the risk of complications from influenza if it is used as a therapeutic agent.

Nonspecific agents (immunal, amiksin, alisat) cannot fully protect against influenza, since they are not capable of inducing stable specific anti-influenza immunity.

Incubation period with flu continues 12-48 hours.

The influenza virus belongs to the group of respiratory viruses (virus influenza). The disease is transmitted by airborne droplets, but it is also possible transplacental transmission virus from mother to fetus.

Influenza viruses are representatives family Orthomyxoviridae, including types A,IN And WITH.

Influenza A viruses are divided into subtypes based on the antigenic properties of the surface hemagglutinin (H) And neuraminidase (N). Individual strains are also distinguished depending on the place of origin, number of isolates, year of isolation and subtypes (for example, influenza A (Victoria) 3/79GZN2).

Influenza A virus genome segmented, consists of 8 single-stranded segments of viral RNA. Due to this segmentation, the probability of gene recombination is high.

The influenza virus is a pantropic viruses; None of the known influenza virus strains has true neurotropic properties. It is known that the influenza virus has a toxic effect on the vascular endothelium, in particular brain vessels.

Pathogenetic mechanisms with influenza infection there are neurotoxicosis and dyscirculatory phenomena in the brain.

Nervous system lesions often occur with influenza. Both its central and peripheral parts suffer. The clinical picture is characterized by great polymorphism.

Damage to the nervous system occurs in all cases of influenza and is manifested by the following symptoms, which relate to general infectious and general cerebral symptoms: regular flu:
headache
pain when moving the eyeballs
muscle pain
adynamia
drowsiness or insomnia

Severity of nervous disorders With this infection, it can vary: from mild headaches to severe encephalopathy and allergic encephalitis, involving the brain in the process.

The following clinical forms of influenza with damage to the nervous system are described, occurring in the form of:
meningitis
meningoscephalitis
encephalitis
encephalomyelitis
myelitis
neuritis (at any level of the nervous system - neuralgia trigeminal nerve, large occipital nerve, auditory neuropathy and oculomotor nerves)
radiculitis (lumbosacral and cervical level)
polyneuritis
lesions of the sympathetic nodes

Lesions of the nervous system are often observed with toxic forms of influenza. Complications arise acutely or subacutely both during the febrile period and during the extinction of influenza infection, and sometimes much later. The most common signs of general toxicosis are: rapid rise body temperature up to 39-40°C and above, headaches, dizziness, single or double vomiting. These signs are quite frequent and constant. They are usually more pronounced the more severe they are infectious process. They indirectly indicate an increase intracranial pressure. Changes in the respiratory system(cough, runny nose, etc.) usually complement the flu clinic; they are very frequent, but far from constant.

Constant symptoms influenza toxicosis are signs of damage vegetative department central nervous system, which has a variety of functions and regulates the activity of internal organs: heart, lungs, organs gastrointestinal tract. Scientists have found that particularly dramatic changes occur in hypothalamic region, where the highest regulatory centers of the autonomic nervous system are located.

Damages to the nervous system are a consequence of both direct impact influenza virus and general infectious diseases And toxic influences

Pathomorphological changes inflammatory and toxic in nature in the form of lymphoid and plasma infiltrates around the vessels, hemorrhages, thrombovasculitis, dystrophy nerve cells are found:
in and around vessels
in ganglion cells
in gliotic elements

IN cerebrospinal fluid are found:
slight pleocytosis
moderate increase in protein content
increased cerebrospinal fluid pressure

In blood leukocytosis or leukopenia is determined.

Flow- favorable, the disease lasts from several days to a month and ends with complete recovery.

!!! But in acute period illness with influenza may develop severe damage to the nervous system in the form influenza encephalitis.

Let's take a closer look at influenza encephalitis and influenza psychosis, which often accompanies influenza encephalitis.

Influenza encephalitis

Called influenza viruses A1, A2, AZ, B. Occurs as a complication of viral influenza.

The question of the origin of influenza encephalitis has not yet been resolved. Along with undoubted cases of this disease, secondary to viral influenza, especially in its toxic form, there is reason to believe that there is primary influenza encephalitis.

The clinical expression of influenza encephalitis cannot be reduced to any one more or less typical type. Most frequent forms influenza encephalitis are:
acute hemorrhagic encephalitis
diffuse meningoencephalitis
limited meningoencephalitis

Acute hemorrhagic encephalitis
Disease begins with typical signs of influenza infection: weakness, malaise, chills, discomfort V various parts bodies, especially in small joints, catarrh of the upper respiratory tract. Headache occurs more often than with normal flu. A pronounced temperature reaction does not always occur, so a person often continues to work and is treated on an outpatient basis. About a week after the first symptoms appear Influenza illness develops insomnia, a feeling of anxiety and unaccountable fear arises, and vivid visual and auditory hallucinations of frightening content appear. Particularly characteristic for hemorrhagic encephalitis, sudden motor agitation. At first, it seems to be justified: patients defend themselves from imaginary danger inspired by fear and hallucinatory experiences, enter into arguments with hallucinatory images, rush to flight and can hardly be kept in bed. Further motor excitation takes on the character of meaningless, involuntary hyperkinesis: patients perform swimming movements and stereotypically move their legs. As the disease progresses hyperkinesis intensifies and stunned consciousness occurs, reaching stupor and coma.

Diffuse meningoencephalitis
Meningoencephalitis is often observed in the toxic form of influenza and, according to many authors, is nothing more than a secondary reaction to infectious toxicosis. Toxic meningoencephalitis clinically resembles hemorrhagic encephalitis, but differs more benign course, frequent remissions and usually ends in recovery. The most characteristic symptom toxic meningoencephalitis, except the usual neurological disorders(oculomotor disorders, headaches, vomiting), is anxious-depressive mood. Patients cannot explain what inspired this feeling of anxiety in them. Further as if for the second time a violation of the interpretation of the surrounding situation arises, the patients begin to feel that something is being plotted against them. They claim that loved ones and caregivers medical staff dramatically changed their attitude towards them. Thoughts about imminent violent death appear. This delusional mood is supported not only by a feeling of anxiety, but also by often occurring auditory and visual hallucinations. Patients usually hear unpleasant remarks, swearing, threats, ambiguous jokes, the voices of their loved ones behind the partition, etc. In those cases, when the first place in the clinical picture is occupied not by hallucinatory experiences, but by depressive-paranoid phenomena, the disease proceeds with less pronounced neurological signs of meningo-encephalitis and tends to have a protracted course. Meningo-encephalitis with delirious-depressive syndrome usually ends in remission within several weeks.

Limited meningoencephalitis
Limited meningoencephalitis appears to be the most common brain disease associated with influenza. Due to various localizations The clinical picture of these meningoencephalitis differs significant polymorphism. There are frequent cases when such meningo-encephalitis carried on legs and in acute stage illness is nothing but usual signs influenza infection is not observed. After the disappearance of acute symptoms symptoms are detected focal lesion cerebral cortex, which in the acute period are usually masked by general clinical signs influenza infection. In childhood limited meningoencephalitis often has the so-called psychosensory form. The acute period of the disease is characterized by a sudden onset and daily increases in temperature or fluctuations throughout the week from 37 to 39°. As a rule, severe headaches with nausea and vomiting are observed. Catarrhal phenomena in the form of a runny nose, cough, as well as sore throat and various painful sensations, especially in the abdominal area, are observed in the acute period with noticeable consistency and are taken for the usual picture of influenza. At the height of the acute period stunned consciousness and episodic visual hallucinations develop. Patients complain of darkening, fog and smoke in the eyes, a feeling of weightlessness, unevenness of the floor surface, soil, metamorphopsia. From neurological symptoms convergence paresis and vestibular disorders, from somatic disorders - esterocolitis and hepatitis. Generally forecast good for the psychosensory form of limited meningoencephalitis. Acute symptoms disappear and children return to school. Long-term asthenia is often observed. However residual effects in this form occur quite often and consist mainly in the fact that upon further exposure to any external factors(repeated infections, intoxication, trauma) psychosensory disorders recur.

PATHOLOGICAL ANATOMY

In influenza encephalitis, the process involves predominantly shell And bark brain.

For hemorrhagic encephalitis diffuse damage to the blood vessels of the brain is detected, expressed in their expansion, hemostasis and perivascular hemorrhages. The substance of the brain is full-blooded, has a characteristic pinkish tint and is flabby to the touch. On microscopic examination Diffuse vasculitis is detected in the form of swelling of the vascular endothelium, perivascular edema and massive diapedesis of red blood cells. Hemorrhagic couplings around small vessels are found equally often in both the cerebral cortex and the subcortex.

For general toxic meningoencephalitis hemostasis phenomena are much less pronounced. Protein perivascular edema comes to the fore both in the substance of the brain and in the membranes. In exudate, as a rule, there are no cellular elements or a small number of leukocytes and plasma cells are found.

At limited meningo-encephalitis the same changes are observed. Their favorite location is temporoparietal lobe and infundibulum of the middle ventricle. The neurological picture of limited meningoencephalitis also depends on the location. Known cases localization of the process in the area of ​​the chiasm optic nerves, which often leads to blindness. Arachnoiditis and glial scars that arise at the site of former infiltrates and exudates disrupt the circulation of cerebrospinal fluid and cause hypertensive disorders, less often hydrocephalus. Along with focal residual phenomena, signs of general damage are also noted.

FLU PSYCHOSIS

1. With a toxic form of influenza, a picture may be observed delirious syndrome , which usually lasts several hours and less often - 2 days.

2. Most often, influenza psychosis manifests itself amentive syndrome . It develops by the time the temperature has already dropped. In this case, memory impairments occur for current and recently past events. The disease lasts from 1 1/2 - 2 weeks to 2 months and ends with recovery.

3. Encephalitic form of influenza psychosis . In some cases, it occurs with a psychopathological picture of influenza delirium, which, however, takes on a more protracted nature (for 1 1/2 - 2 weeks) and is accompanied by neurological symptoms. May be observed in this case various lesions cranial nerves, violent and involuntary movements, ataxia phenomena, aphasic speech disorders. In some patients, delirium transforms into mild symptoms severe depression with symptoms of depersonalization, derealization and hypopathy. This syndrome can last for several months, gradually fading. In other cases, it occurs without previous delirium. All these symptoms gradually regress, and the patients get better, but sometimes they still have both neurological and psychopathological residual phenomena. Patients become affectively unstable and prone to conflicts. Their performance decreases. Especially sudden violations observed in persons who have had influenza encephalitis in adolescence.

4. Another type of encephalitic form of influenza psychosis is psychopathologically expressed in the picture severe delirium , which was described by old psychiatrists under the name of acute delirium. Usually there is a sudden deep blackout with complete disorientation. Speech becomes completely incoherent and consists of a set of individual phrases, words and syllables, when listening to which it is difficult to penetrate into the content of the hallucinatory-delusional experiences of patients. Patients are in a state of extreme motor agitation. Movements at the height of excitement lose all coordination. Convulsive twitching appears in various parts of the body. Various performers neurological symptoms in the form of ptosis, strabismus, uneven tendon reflexes. The pupils are usually dilated and react sluggishly to light. Then a weakening of cardiac activity appears. The temperature at this time is high (39 - 40°). In this condition, patients most often die. The disease lasts from several days to 2 - 3 weeks. Characteristic is the presence of blood in cerebrospinal fluid. This type of influenza encephalitic psychosis can be called hemorrhagic.

DIAGNOSIS of influenza encephalitis

Diagnostics based to detect high titers of antibodies to these viruses in the blood and cerebrospinal fluid.

Flu can be diagnosed V acute phase by isolating the virus from the oropharynx or nasopharynx (smears, washings) or from sputum on tissue culture 48-72 hours after inoculation.

Antigenic composition of the virus can be determined earlier using immunotechniques on tissue culture or directly in deflated nasopharyngeal cells obtained from lavages, although latest techniques less sensitive than virus isolation.

Retrospective diagnosis possible with a 4-fold or greater increase in antibody titer between two studies - in the acute phase and after 10-14 days. This refers to the following methods: ELISA, hemagglutination inhibition reactions.

TREATMENT

Used in the treatment of influenza encephalitis antivirus agents(acyclovir, interferon, remantadine, arbidol, etc.), carry out activities aimed at prevention and elimination of cerebral edema, detoxification of the body, appoint symptomatic remedies , including psychotropic ones.

Treatment for uncomplicated influenza infection is in alleviating symptoms; Salicylates should not be given to children under 18 years of age due to a possible connection between their use and the occurrence of Reye's syndrome.

Amantadine (200 mg/day orally) is prescribed in cases severe course diseases. Amantadine reduces the duration of general and respiratory symptoms disease by 50%, when starting treatment in the first 48 hours from the onset of the disease at a dose of 200 mg per day orally; Duration of therapy is 3-5 days or 48 hours after the symptoms of the disease disappear. Amantadine is active only against influenza A virus and causes moderate side effects from the central nervous system (excitement, anxiety, insomnia) in 5-10% of patients.

Remantadine, which is very close to amantadine, is equal to it in effectiveness and is less likely to cause side effects.

Ribavirin has been reported to be effective against both types of influenza viruses (A and B) when administered as an aerosol, but less effective when administered orally.

Also prescribeddehydrating(25% magnesium sulfate solution, 40% glucose solution, Lasix) and desensitizing(diphenhydramine, pipolfen) agents, calcium gluconate, rutin, ascorbic acid, thiamine chloride, sedatives.

PREVENTION

An important means of prevention influenza neurological complications is primarily the prevention of influenza itself, which is carried out through influenza vaccination.

Sick with influenza until body temperature normalizes and catarrhal symptoms disappear should be released from work.

Along with anti-influenza drugs medications should be used, increasing protective forces body, provide nutrition with high energy value, good care, room ventilation, etc.

To prevent influenza annually carry out vaccinations against influenza A and B; use inactivated vaccine, obtained from virus strains that circulated in the population in the past year. Vaccination recommended children over 6 years of age with chronic pulmonary and cardiovascular diseases, disabled people living in boarding houses and in need of constant care, persons over 65 years of age, healthcare workers, patients with diabetes, kidney damage, hemoglobinopathies or immunodeficiency. Inactivated vaccine can be used in patients with immunodeficiency.

Live attenuated vaccine against influenza A is used intranasally in children and adults.